Method for sending channel information, and a terminal, a base station and an LTE-A system

ABSTRACT

The present invention discloses a method for sending channel information, and a terminal, a base station and an LTE-A system. The method comprises: a mobile terminal acquiring channel information; determining, in a codebook space, an RI and a PMI corresponding to the channel information according to the channel information; and sending the RI and the PMI to a base station. By way of the present invention, the effects of improving the throughput of an LTE-A system and the frequency spectrum efficiency thereof are achieved.

FIELD OF THE INVENTION

The present invention relates to the communication field, andspecifically to a method for sending channel information, and aterminal, a base station and a Long-term Evolution Advance (LTE-A)system.

BACKGROUND OF THE INVENTION

In a wireless communication system, a sending terminal and a receivingterminal use multiple antennae to obtain a higher speed in a manner ofspatial multiplexing. Compared to general spatial multiplexing manner,an enhanced technology is one that the receiving terminal feeds channelinformation back to the sending terminal which uses some transmissionprecoding technologies according to the channel information acquired,thus improving the transmission performance significantly. Forsingle-user Multi-Input Multi-Output (MIMO), precoding is performed bydirectly using channel characteristic vector information; while formultiple-user MIMO, more precise channel information is required.

The channel information is fed back mainly through a simple singlecodebook feedback method in the Long Term Evolution (LTE), while theperformance of the MIMO transmission precoding technology depends moreon the feedback accuracy of the codebook adopted.

In the related art, the basic principle of the quantized feedback of thecodebook-based channel information is as follows.

Assuming that a limited feedback channel capacity is B bps/Hz, then thenumber of available code words is. N=2^(B). The characteristic vectorspace of a channel matrix constructs a codebook space

={F₁, F₂, . . . F_(N)} through quantization. The sending and receivingterminals store the codebook together or generate the codebook in realtime (the sending and receiving terminals use the same codebook). For achannel estimate value H realized for the channel each time, thereceiving terminal selects, from

, a code word {circumflex over (F)} most matching with the channelaccording to certain rules and feeds the serial number i of the codeword back to the sending terminal. The serial number of the code word iscalled Precoding Matrix Indicator (PMI) herein. The sending terminalfinds the corresponding precoding code word {circumflex over (F)}according to the serial number i of the code word, thus obtaining thecorresponding channel information, wherein {circumflex over (F)}represents the characteristic vector information of the channel.

Generally, the codebook space

can be further divided into the codebook corresponding to multiple Ranks(number of layers), wherein each Rank corresponds to multiple code wordsfor quantizing the precoding matrix composed of the channelcharacteristic vectors under the Rank. Since the Rank of the channel isequal to the number of non-zero characteristic vectors, there will be Ncolumns of code words when the Rank is N. Therefore, the codebook space

can be divided into multiple sub-codebooks according to the Rank, asshown in Table 1.

TABLE 1 Schematic table of dividing the codebook into multiplesub-codebooks according to the Rank

number of layers υ (Rank) 2 . . . N

 ₁

 ₂ . . .

 _(N) set of code set of code set of code word word vectors with wordmatrixes matrixes with N columns 1 column with 2 columns

Wherein, when the Rank>1, all the code words required to be stored arein the form of matrix. The codebook in the LTE protocol uses thiscodebook quantization feedback method. The codebook for downlink 4transmitting antennae in the LTE is as shown in Table 2. In fact, theprecoding codebook in the LTE has the same meaning with the channelinformation quantization codebook. For uniformity's sake, the vector canbe regarded as a matrix with a dimension of 1 in this application.

TABLE 2 Schematic table of codebook for downlink 4 transmitting antennaein LTE Code book Total number of layers υ Index u_(n) 1 2 3 4 0  u₀ = [1−1 −1 −1]^(T) W₀ ^({1})  W₀ ^({14})/{square root over (2)}  W₀^({124})/{square root over (3)}  W₀ ^({1234})/2 1  u₁ = [1 −j 1 j]^(T)W₁ ^({1})  W₁ ^({12})/{square root over (2)}  W₁ ^({123})/{square rootover (3)}  W₁ ^({1234})/2 2  u₂ = [1 1 −1 1]^(T) W₂ ^({1})  W₂^({12})/{square root over (2)}  W₂ ^({123})/{square root over (3)}  W₂^({3214})/2 3  u₃ = [1 j 1 −j]^(T) W₃ ^({1})  W₃ ^({12})/{square rootover (2)}  W₃ ^({123})/{square root over (3)}  W₃ ^({3214})/2 4  u₄ = [1(−1 − j)/{square root over (2)} −j (1 − j)/{square root over (2)}]^(T)W₄ ^({1})  W₄ ^({14})/{square root over (2)}  W₄ ^({124})/{square rootover (3)}  W₄ ^({1234})/2 5  u₅ = [1 (1 − j)/{square root over (2)} j(−1 − j)/{square root over (2)}]^(T) W₅ ^({1})  W₅ ^({14})/{square rootover (2)}  W₅ ^({124})/{square root over (3)}  W₅ ^({1234})/2 6  u₆ = [1(1 + j)/{square root over (2)} −j (−1 + j)/{square root over (2)}]^(T)W₆ ^({1})  W₆ ^({13})/{square root over (2)}  W₆ ^({134})/{square rootover (3)}  W₆ ^({1324})/2 7  u₇ = [1 (−1 + j)/{square root over (2)} j(1 + j)/{square root over (2)}]^(T) W₇ ^({1})  W₇ ^({13})/{square rootover (2)}  W₇ ^({134})/{square root over (3)}  W₇ ^({1324})/2 8  u₈ = [1−1 1 1]^(T) W₈ ^({1})  W₈ ^({12})/{square root over (2)}  W₈^({124})/{square root over (3)}  W₈ ^({1234})/2 9  u₉ = [1 −j −1 −j]^(T)W₉ ^({1})  W₉ ^({14})/{square root over (2)}  W₉ ^({134})/{square rootover (3)}  W₉ ^({1234})/2 10 u₁₀ = [1 1 1 −1]^(T) W₁₀ ^({1}) W₁₀^({13})/{square root over (2)} W₁₀ ^({123})/{square root over (3)} W₁₀^({1324})/2 11 u₁₁ = [1 j −1 j]^(T) W₁₁ ^({1}) W₁₁ ^({13})/{square rootover (2)} W₁₁ ^({134})/{square root over (3)} W₁₁ ^({1324})/2 12 u₁₂ =[1 −1 −1 1]^(T) W₁₂ ^({1}) W₁₂ ^({12})/{square root over (2)} W₁₂^({123})/{square root over (3)} W₁₂ ^({1234})/2 13 u₁₃ = [1 −1 1 −1]^(T)W₁₃ ^({1}) W₁₃ ^({13})/{square root over (2)} W₁₃ ^({123})/{square rootover (3)} W₁₃ ^({1324})/2 14 u₁₄ = [1 1 −1 −1]^(T) W₁₄ ^({1}) W₁₄^({13})/{square root over (2)} W₁₄ ^({123})/{square root over (3)} W₁₄^({3214})/2 15 u₁₅ = [1 1 1 1]^(T) W₁₅ ^({1}) W₁₅ ^({12})/{square rootover (2)} W₁₅ ^({123})/{square root over (3)} W₁₅ ^({1234})/2

In the above, W_(n)=I−2u_(n)u_(n) ^(H)/u_(n) ^(H)u_(n), I is an identitymatrix, W_(k) ^((j)) represents the vector of Column j of Matrix W_(k),and W_(k) ^((j) ¹ ^(,j) ² ^(, . . . j) ^(n) ⁾ represents the matrixcomposed of Columns j₁, j₂, . . . j_(n) of Matrix W_(k).

The above is the basic principle of the codebook feedback technology. Inthe practical application of the system, some specific parameters may beinvolved. In the LTE standard, the minimum feedback unit of the channelinformation is a Subband; one Subband is composed of several resourceblocks (RB) which consists of multiple resource elements (RE), whereinan RE is the minimum unit of the time frequency resources in the LTEsystem. The resource expression method of LTE is still used in theLTE-A. The object of the channel information feedback of the userequipment can be anyone of the Subband, multiple Subbands(Multi-Subband) and Wideband.

The feedback of the channel state information comprises: a ChannelQuality Indication (CQI), a Precoding Matrix Indicator (PMI) and a RankIndicator (RI).

PMI represents characteristic vector information, and it is sent to thebase station to be used for the downlink precoding technology.

RI is used to describe the number of the space independent channels, andcorresponds to the Rank of a channel response matrix. In open-loop andclosed-loop spatial multiplexing modes, the RI information is requiredto be fed back by the UE, while in other modes, the RI information isnot required to be fed back. The Rank of the channel matrix correspondsto the number of layers.

CQI is an indication for evaluating the quality of the downlink channel.In the 3GPP 36-213 protocol, CQI is expressed by the integral valueswithin 0˜15, representing different CQI levels respectively, whereindifferent CQIs correspond to their own Modulation Codes and coding rates(Modulate Code format Set, MCS). The CQI can be fed back together withthe PMI.

With the development of the communication technology, the LTE-Advancesystem has a higher requirement for the frequency spectrum efficiency.Therefore, the number of antennae is increased to 8. At present, thecodebook for 4 antennae in the LTE system can not realize the channelinformation feedback in the LTE-A using 8 antennae.

SUMMARY OF THE INVENTION

The present invention mainly provides a method for sending channelinformation, and a terminal, a base station and an LTE-A system, so asto at least solve the problem above that the codebook for 4 antennae inthe LTE system can not realize the channel information feedback in theLTE-A system using 8 annotate.

According to one aspect of the present invention, a method for sendingchannel information is provided.

The method for sending channel information according to the presentinvention comprises: a mobile terminal acquiring channel information;according to the channel information, determining, in a codebook space,a Rank Indicator (RI) and a Precoding Matrix Indicator (PMI)corresponding to the channel information; and sending the RI and the PMIto a base station.

After the step of sending the RI and the PMI to the base station, themethod further comprises: the base station acquiring the RI and the PMI;and performing downlink precoding operation according to the RI and thePMI.

The codebook space is stored in both the mobile terminal and the basestation.

When the RI is equal to 8, a codebook space

₈ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows:

the set is

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\{\; X_{1}} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},\left. \quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\{\;{j\; X_{m}}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\},{{{wherein}\mspace{14mu} X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}} \right.$

When the RI is equal to 7, a codebook space

₇ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows:

the set is

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\{\; Z_{1}} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{\; Z_{2}} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{\;{j\; Z_{1}}} & {{- j}\; X_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{\;{j\; Z_{2}}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{\; Z_{3}} & {- X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{\; Z_{4}} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{\;{j\; Z_{3}}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{{- j}\; Z_{3}} & {j\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{\;{j\; Z_{4}}} & {{- j}\; X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{{- j}\; Z_{4}} & {j\; X_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{\; Z_{m}} & {- X_{n}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{\;{{- j}\; Z_{m}}} & {j\; X_{n}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{j\; Z_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\},}}}}}}} \right.$wherein Z₁ and Z₂ are both 4×3 matrixes, Z₁ is composed of any 3 columnsin X₁, and Z₂ is composed of any 3 columns in X₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

When the RI is equal to 6, a codebook space

₆ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows:

the set is

$\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\{\; Z_{1}} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & Z_{3} \\Z_{3} & {- Z_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\begin{bmatrix}Z_{3} & Z_{3} \\{j\; Z_{3}} & {{- j}\; Z_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\{j\; Z_{4}} & {{- j}\; Z_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {- Z_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\{\;{j\; Z_{m}}} & {{- j}\; Z_{n}}\end{bmatrix}}}} \right\},} \right.$wherein Z₁ and Z₂ are both 4×3 matrixes, Z₁ is composed of any 3 columnsin X₁, and Z₂ is composed of any 3 columns in X₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄,

${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

When the RI is equal to 5, a codebook space

₅ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows,

the set is

$\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\{\; Z_{1}} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{\; Z_{2}} & {- M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{\;{j\; Z_{1}}} & {{- j}\; M_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {j\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{\;{j\; Z_{2}}} & {{- j}\; M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & M_{3} \\{\; Z_{3}} & {- M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{\; Z_{4}} & {- M_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & M_{3} \\{\;{j\; Z_{3}}} & {{- j}\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{{- j}\; Z_{3}} & {j\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{\;{j\; Z_{4}}} & {{- j}\; M_{4}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{\; Z_{m}} & {- X_{n}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & M_{j} \\{\;{{- j}\; Z_{m}}} & {j\; M_{j}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & M_{n} \\{j\; Z_{m}} & {{- j}\; M_{n}}\end{bmatrix}}}} \right\},}}}}}}} \right.$wherein Z₁ and Z₂ are both 4×3 matrixes, Z₁ is composed of any 3 columnsin X₁, Z₂ is composed of any 3 columns in X₂, Z₃ is composed of any 3columns in X₃, and Z₄ is composed of any 3 columns in X₄; or Z₁ iscomposed of any 3 columns in X₁, Z₂ is composed of any 3 columns in X₃,Z₃ is composed of any 3 columns in X₂, and Z₄ is composed of any 3columns in X₄; M₁ and M₂ are both 4×2 matrixes, M₁ is composed of any 3columns in Z₁, and M₂ is composed of any 3 columns in Z₂; M₃ and M₄ areboth 4×2 matrixes, M₃ is composed of any 3 columns in Z₃, and M₄ iscomposed of any 3 columns in Z₄;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

The codebook is in a form of multiplying a fixed matrix M by anothercodebook C, and the product of M and C is equivalent to the codebook.

Exchange of any columns of the codebook is an equivalent transformationof the codebook, and exchange of any rows of the codebook is anequivalent transformation of the codebook.

Multiplying of any one column of the codebook and any constantcoefficient with a module of 1 is an equivalent transformation of thecodebook.

The product obtained by multiplying all the columns of the codebook byany non-zero constant coefficient is equivalent to the codebook.

According to another aspect of the present invention, a mobile terminalis provided.

The mobile terminal according to the present invention comprises: afirst acquiring module, configured to acquire channel information; adetermination module, configured to determine, in a codebook space, anRI and a PMI corresponding to the channel information according to thechannel information, and a sending module, configured to send the RI andthe PMI to a base station.

According to still another aspect of the present invention, a basestation is provided.

The base station according to the present invention comprises: a secondacquiring module, configured to acquire an RI and a PMI; and a precodingmodule, configured to perform downlink precoding operation according tothe RI and the PMI.

According to still another aspect of the present invention, an LTE-Asystem is provided. The LTE-A system comprises: the above mobileterminal and the above base station.

By way of the present invention, a terminal acquires channelinformation, an RI and a PMI corresponding to the channel informationare determined in a codebook space according to the channel information,and the RI and the PMI are sent to a base station, the above-mentionedproblem that the codebook with 4 antennae in the LTE system can notrealize the channel information feedback in the LTE-A using 8 antennaeis solved, and the effects of improving the throughput of an LTE-Asystem and the frequency spectrum efficiency thereof are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Drawings, provided for further understanding of the present inventionand forming a part of the specification, are used to explain the presentinvention together with embodiments of the present invention rather thanto limit the present invention, wherein:

FIG. 1 is a flow chart of a method for sending channel informationaccording to an embodiment of the present invention;

FIG. 2 is a structural block diagram of a mobile terminal according toan embodiment of the present invention;

FIG. 3 is a structural block diagram of a base station according to anembodiment of the present invention; and

FIG. 4 is a structural block diagram of an LTE-A system according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be further illustrated hereinafter inconjunction with the exemplary embodiments and accompanying drawings. Itshall be noted that the embodiments in the present invention and thecharacteristics in the embodiments can be mutually combined if noconflict occurs.

According to an embodiment of the present invention, a method forsending channel information is provided. FIG. 1 is a flow chart of themethod for sending channel information according to the embodiment ofthe present invention. As shown in FIG. 1, the method comprises:

S102: a terminal acquires channel information.

S104: an RI and a PMI corresponding to the channel information aredetermined in a codebook space according to the channel information, and

S106: the RI and the PMI are sent to a base station.

Through the steps above, an RI and a PMI corresponding to the channelinformation are determined in a codebook space according to the channelinformation acquired by the terminal, and the RI and the PMI are sent toa base station, thus the above-mentioned problem that the codebook spacewith 4 antennae in the LTE system in related art can not realize thechannel information feedback in the LTE-A using 8 antennae is solved,and the effects of improving the throughput of an LTE-A system and thefrequency spectrum efficiency thereof are achieved.

Preferably, after S106, the above methods also comprises: the basestation acquires the RI and the PMI, and performs a downlink precodingoperation according to the RI and the PMI. Through the precodingoperation in the preferable embodiment, the precoding is performedaccording to the acquired RI and PMI, thus improving the frequencyspectrum efficiency of the LTE-A system.

Preferably, S102 comprises: the mobile terminal acquires the channelinformation by estimating the channel according to the downlink pilotfrequency. Through the acquiring operation in the preferable embodiment,the mobile terminal acquires the channel information by estimating thechannel according to the downlink pilot frequency, in this way, thefully-developed existing channel estimation technology can be usedwithout changing the existing method, and further saves the developmentcost.

Preferably, the codebook space above is stored on the mobile terminaland the base station simultaneously. Through the preferable embodiment,the uniform codebook space stored in the base station and the codebookspace ensures the sending accuracy of the channel information.

Preferably, when RI is equal to 8, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₈;

the set is

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\{\; X_{1}} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\{\;{j\; X_{m}}} & {{- j}\; X_{n}}\end{bmatrix}}}}}} \right\},{{{wherein}\mspace{14mu} X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{m \neq n},{m \in \left\{ {1,2,3,4} \right\}},{n \in {\left\{ {1,2,3,4} \right\}.}}$

Preferably, codebook space

₈, composed of two code words, is constructed through one of thefollowing construction methods.

Construction method 1:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] } ;

Construction method 2:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 1 X 1 j ⁢ ⁢ X 1 - j ⁢ ⁢ X 1 ] } ; or${}_{8} = {\left\{ {\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix}} \right\}.}$It shall be noted that Construction method 1 and Construction method 2can be realized by selecting any two from the set

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix}} \right\}.$

Codebook space

₈, composed of 4 code words, can be determined through one of thefollowing construction methods.

Construction method 3:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 1 X 1 j ⁢ ⁢ X1 - j ⁢ ⁢ X 1 ] , [ X 2 X 2 j ⁢ ⁢ X 2 - j ⁢ ⁢ X 2 ] } ;

Construction method 4:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] } .

It shall be noted that Construction method 3 and Construction method 4can be realized by selecting any 4 from the set

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},{\left. \quad{\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix}} \right\}.}}}} \right.$Codebook space

₈, composed of 8 code words, can be determined through one of thefollowing construction methods.

Construction method 5:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] , ⁢   [ X m X n X m - X n ] , [ X m X n X m -X n ] , [ X m X n X m - X n ] , [ X m X n X m - X n ] } ; ⁢ ( m ≠ n , m ∈{ 1 , 2 , 3 , 4 } , n ∈ { 1 , 2 , 3 , 4 } )

Construction method 6:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] , ⁢   [ X 1 X 2 X 1 - X 2 ] , [ X 2 X 3 X 2 -X 3 ] , [ X 3 X 4 X 3 - X 4 ] , [ X 4 X 1 X 4 - X 1 ] } ;

Construction method 7:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] ,   [ X 1 X 2 X 1 - X 2 ] , [ X 1 X 3 X 1 -X 3 ] , [ X 1 X 4 X 1 - X 4 ] , [ X 2 X 3 X 2 - X 3 ] } .

It shall be noted that Construction Methods 5-7 can be realized byselecting any 4 from the set

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},{\quad{\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\left. \quad{\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix}} \right\}}}}}} \right.$and any 4 from the set

$\left\{ {{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\{j\; X_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\}.$

Wherein

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{l - {\mathbb{i}}}{\sqrt{2}}.}}$=By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank8 (RI=8) is provided,thus improving the precoding performance of the system in the case ofRank8 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, the codebook space

₈ is in the form of the multiplying of a fixed matrix M and anothercodebook space C8, and the product of M and C8 is equivalent to thecodebook space

₈, namely the codebook space

₈ can be in the form of the multiplying of a fixed matrix M and anothercodebook C8. Although the codebook space actually used is C8, it isrequired to multiply C8 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₈.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₈ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₈ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₈ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₈.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₈ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₈.

Preferably, when RI is equal to 7, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₇:

the  set  is  $\mspace{11mu}\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{j\; Z_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{{- j}\; Z_{3}} & {j\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{j\; Z_{4}} & {{- j}\; X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{{- j}\; Z_{4}} & {j\; X_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{{- j}\; Z_{m}} & {j\; X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{j\; Z_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\}.}}}}}}}}}} \right.$

Codebook space

₇, composed of two code words, can be constructed through one of thefollowing construction methods.

Construction method 8:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] } ;

Construction method 9:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X 2 ] } ;

Construction method 10:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 1 X 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ X 1 ] } ;

Construction method 11:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] } ;

Construction method 12:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] } ;

Construction method 13:

${\;_{7} = \left\{ {\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix}} \right\}};$wherein, in Construction methods 8 to 13, Z₁ and Z₂ are 4×3 matrixes, Z₁is composed of any 3 columns in X₁, and Z₂ composed of any 3 columns inX₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

It shall be noted that, the Construction methods 8-13 are realized byselecting any 2 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix}} \right\}.}} \right.$

Codebook space

₇, composed of 4 code words, can be constructed through one of thefollowing construction methods.

Construction method 14:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] , [ Z 2 X2 - Z 2 X 2 ] , [ Z 2 X 2 - j ⁢ ⁢ Z 2 j ⁢ ⁢ X 2 ] } ;

Construction method 15:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] , [ Z 2 X 2Z 2 - X 2 ] , [ Z 2 X 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ X 2 ] } ;

wherein, in Construction methods 14 and 15, Z₁ is composed of any 3columns in X₁, and Z₂ is composed of any 3 columns in X₂; or Z₁ iscomposed of any 3 columns in X₂, and Z₂ is composed of any 3 columns inX₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 16:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X2 ] , [ Z 2 X 2 Z 2 - X 2 ] } ;wherein, in Construction method 16, Z₁ is composed of any 3 columns inX₁, and Z₂ is composed of any 3 columns in X₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = {\begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}.}}$

It shall be noted that Construction methods 14, 15 and 16 are realizedby selecting any 4 matrixes from the set

$\left\{ {{{{\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix}\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix}}{\left. \quad{\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},{{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix}\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix}}} \right\}.}} \right.$

Construction method 17:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ;

Construction method 18:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ,

wherein, in Construction methods 17 and 18, Z₁ is composed of any 3columns in X₁, Z₂ is composed of any 3 columns in X₂, Z₃ is composed ofany 3 columns in X₃, and Z₄ is composed of any 3 columns in X₄; or Z₁ iscomposed of any 3 columns in X₁, Z₂ is composed of any 3 columns in X₃,Z₃ is composed of any 3 columns in X₂, and Z₄ is composed of any 3columns in X₄;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

It shall be noted that Construction methods 17 and 18 are realized byselecting any 4 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix}{\quad{,{\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix}{\left. \quad{,\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix}} \right\}.}}}}}}}}} \right.$

By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank7 (RI=7) is provided,thus improving the precoding performance of the system in the case ofRank7 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, codebook space

₇ is in the form of the multiplying of a fixed matrix M and anothercodebook C7, and the product of M and C7 is equivalent to the codebookspace

₇, namely the codebook space

₇ can be in the form of the multiplying of a fixed matrix M and anothercodebook C7. Although the codebook space actually used is C7, it isrequired to multiply C7 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₇.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₇ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₇ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₇ and any constant coefficient with a module of 1 is equivalenttransformation of the codebook space

₇.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivilant tothe codebook space. Namely, the multiplying of all the columns of

₇ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₇.

Preferably, when RI is equal to 6, any 2, 4, 8 or 16 matrixes areselected from the following to construct codebook space

₆:

the set is

$\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{3} & Z_{3} \\{\; Z_{3}} & {- Z_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\begin{bmatrix}Z_{3} & Z_{3} \\{j\; Z_{3}} & {{- j}\; Z_{3}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{4} & Z_{4} \\{j\; Z_{4}} & {{- j}\; Z_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {\;{- Z_{n}}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\{\;{j\; Z_{m}}} & {{- j}\; Z_{n}}\end{bmatrix}}}} \right\}.}}}}}} \right.$

Codebook space

₆, composed of two code words, can be constructed by selecting any 2matrixes from the set below,

the set is

$\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix}} \right\}.$

Codebook space

₆ is determined through one of the following construction methods.

Construction method 19:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] } ;

Construction method 20:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] } ;

wherein, in Construction methods 19 and 20, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in X₂;

${{X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + i}{\sqrt{2}}},{q_{2} = \frac{{- 1} + i}{\sqrt{2}}},{q_{3} = \frac{{- 1} - i}{\sqrt{2}}},{{q_{4} = \frac{1 - i}{\sqrt{2}}};}}\mspace{130mu}$

Codebook space

₆, composed of 4 code words, can be determined through one of thefollowing construction methods:

Construction method 21:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z 2Z 2 - Z 2 ] , [ Z 2 Z 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] } ;

Construction method 22:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] , [ Z 4 Z 4 Z 4 - Z 4 ] } ;

wherein, in Construction methods 21 and 22, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in X₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$=Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄,

${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank6 (RI=6) is provided,thus improving the precoding performance of the system in the case ofRank6 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Codebook space

₆, composed of 8 code words, can be determined through one of thefollowing construction methods:

Construction method 23:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] , [ Z 4 Z 4 Z 4 - Z 4 ] ,   [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] , [ Z 3 Z 3 j ⁢ ⁢ Z 3 - j ⁢ ⁢ Z 3 ] , [ Z 4 Z 4 j ⁢ ⁢ Z4 - j ⁢ ⁢ Z 4 ] } .

Construction method 24:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] , [ Z 4 Z 4 Z 4 - Z 4 ] ,   [ Z 1 Z 2 Z 1 - Z 2 ] , [ Z 1 Z 4 Z 1 -Z 4 ] , [ Z 2 Z 3 Z 2 - Z 3 ] , [ Z 2 Z 4 Z 2 - Z 4 ] } .

Codebook space

₆, composed of 16 code words, can be determined through one of thefollowing construction methods:

Construction method 25:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] ,   [ Z 4 Z 4 Z 4 - Z 4 ] ,   [ Z 1 Z 2 Z 1 - Z 2 ] , [ Z 1 Z 4 Z1 - Z 4 ] , [ Z 2 Z 3 Z 2 - Z 3 ] , [ Z 2 Z 4 Z 2 - Z 4 ] ,   [ Z 1 Z 1j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] , [ Z 3 Z 3 j ⁢ ⁢ Z3 - j ⁢ ⁢ Z 3 ] , [ Z 4 Z 4 j ⁢ ⁢ Z 4 - j ⁢ ⁢ Z 4 ] ,   [ Z 1 Z 2 j ⁢ ⁢ Z 1 - j ⁢⁢Z 2 ] , [ Z 1 Z 4 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 4 ] , [ Z 2 Z 3 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 3 ] ,[ Z 2 Z 4 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 4 ] } .

Preferably, codebook space

₆ is in the form of the multiplying of a fixed matrix M and anothercodebook C6, and the product of M and C6 is equivalent to the codebookspace

₆, namely the codebook space

₆ can be in the form of the multiplying of a fixed matrix M and anothercodebook C6. Although the codebook space actually used is C6, it isrequired to multiply C6 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₆.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₆ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₆ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₆ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₆.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₆ and any constant coefficient which is not 0 is an equivalenttransformation of the codebook space

₆.

Preferably, when RI is equal to 5, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₅:

the set is

$\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{j\; Z_{1}} & {{- j}\; M_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {j\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{j\; Z_{2}} & {{- j}\; M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\Z_{3} & {- M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\Z_{4} & {- M_{4}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{j\; Z_{3}} & {{- j}\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{{- j}\; Z_{3}} & {j\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{j\; Z_{4}} & {{- j}\; M_{4}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{j} \\{{- j}\; Z_{m}} & {j\; M_{j}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{j\; Z_{m}} & {{- j}\; M_{n}}\end{bmatrix}}}} \right\}.}}}}}}}}}} \right.$

Codebook space

₅, composed of two code words, is determined through one of thefollowing construction methods:

Preferably, the construction methods below can be realized by selectingany 2 or 4 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{j\; Z_{1}} & {{- j}\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {j\; M_{1}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{2} & M_{2} \\{j\; Z_{2}} & {{- j}\; M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix}} \right\}.}}}}}} \right.$

Construction method 26:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 2 M 2 Z 2 - M 2 ] } ;

Construction method 27:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M 2 ] } ;

Construction method 28:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 1 M 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ M 1 ] } ;

Construction method 29:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] } ,wherein, Z₁ is 4×3 matrix and is composed of any 3 columns in X₁; M₁ is4×2 matrix and is composed of any 3 columns in Z₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}};$

Construction method 30:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] } ,wherein, Z₁ is 4×3 matrix and is composed of any 3 columns in X₁; M₁ is4×2 matrix and is composed of any 3 columns in Z₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}};$

Construction method 31:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ M 1 ] } ;

wherein, in Construction methods 23 to 28, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in X₂; M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3columns in Z₁, and M₂ is composed of any 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

Codebook space

₅, composed of 4 code words, is determined through one of the followingconstruction methods:

Construction method 32:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 - ⁢ j ⁢ ⁢ M 1 ] , [ Z 2 M2 - Z 2 M 2 ] , [ Z 2 M 2 - j ⁢ ⁢ Z 2 j ⁢ ⁢ M 2 ] } ;

wherein, Z₁ is composed of any 3 columns in X₁, and Z₂ is composed ofany 3 columns in X₂; or X₁ is composed of any 3 columns in X₂, and Z₂ iscomposed of any 3 columns in X₁;

M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3 columns in Z₁, andM₂ is composed of any 3 columns in Z₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 33:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 - ⁢ j ⁢ ⁢ M 1 ] , [ Z 2 M2 Z 2 - M 2 ] , [ Z 2 M 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ M 2 ] } ;

wherein, in Construction methods 32 and 33, Z₁ is composed of any 3columns in X₁, and Z₂ is composed of any 3 columns in X₂; or Z₁ iscomposed of any 3 columns in X₂, and Z₂ is composed of any 3 columns inX₁; M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3 columns in Z₁,and M₂ is composed of any 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 34:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M2 ] , [ Z 2 M 2 Z 2 - M 2 ] } ;

wherein, in Construction methods 34, Z₁ is composed of any 3 columns inX₁, and Z₂ is composed of any 3 columns in X₂; M₁ and M₂ are 4×2matrixes, M₁ is composed of any 3 columns in Z₁, and M₂ is composed ofany 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 35:

5 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ;

Construction method 36:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M 2 ] , [ Z 3 M 3 Z 3 - M3 ] , [ Z 4 M 4 Z 4 - M 4 ] } ;

wherein, in Construction methods 35 and 36, Z₁ is composed of any 3columns in X₁, Z₂ is composed of any 3 columns in X₂, Z₃ is composed ofany 3 columns in X₃, and Z₄ is composed of any 3 columns in X₄; or Z₁ iscomposed of any 3 columns in X₁, Z₂ is composed of any 3 columns in X₃,Z₃ is composed of any 3 columns in X₂ and Z₄ is composed of any 3columns in X₄; M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3columns in Z₁, and M₂ is composed of any 3 columns in Z₂; M₃ and M₄ are4×2 matrixes, M₃ is composed of any 3 columns in Z₃, and M₄ is composedof any 3 columns in

${{Z_{4} \cdot X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2\;}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\;\frac{\pi}{8}} & {\mathbb{e}}^{j\;\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\;\frac{10\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\;\frac{3\pi}{8}} & {\mathbb{e}}^{j\;\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\;\frac{3\pi}{8}} & {\mathbb{e}}^{j\;\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\;\frac{6\pi}{8}} & {\mathbb{e}}^{j\;\frac{14\pi}{8}} & {\mathbb{e}}^{j^{\frac{{- 10}\pi}{8}}} & {\mathbb{e}}^{j\;\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\;\frac{9\pi}{8}} & {\mathbb{e}}^{j\;\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank5 (RI=5) is provided,thus improving the precoding performance of the system in the case ofRank5 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, codebook space

₅ is in the form of the multiplying of a fixed matrix M and anothercodebook C5, and the product of M and C5 is equivalent to the codebookspace

₅, namely the codebook space

₅ can be in the form of the multiplying of a fixed matrix M and anothercodebook C5. Although the codebook space actually used is C5, it isrequired to multiply C5 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₅.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₅ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₅ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₅ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₅.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₅ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₅.

A mobile terminal is provided according to an embodiment of the presentinvention. FIG. 2 is the structural block diagram of the mobileterminal. As shown in FIG. 2, the mobile terminal comprises: a firstacquiring module 22, a determination module 24 and a sending module 26.The structure above will be detailed as follows.

The first acquiring module 22 is configured to acquire channelinformation; the determination module 24, coupled with the firstacquiring module 22, is configured to determine, in a codebook space, anRI and a PMI corresponding to the channel information according to thechannel information acquired by the first acquiring module 22; and thesending module 26, coupled with the determination module 24, isconfigured to sent the RI and the PMI determined by the determinationmodule 24 to a base station.

According to an embodiment of the present invention, a base station isprovided. FIG. 3 is the structural block diagram of the base station. Asshown in FIG. 3, the base station comprises: a second acquiring module32 and a precoding module 34,

the second acquiring module 32 is configured to acquire an RI and a PMI;

the precoding module 34, coupled with the second acquiring module 32, isconfigured to perform downlink precoding operation according to the RIand PMI acquired by the first acquiring module 32.

The mobile terminal and base station use the same codebook space, andthe specific contents of which are as follows.

Preferably, when RI is equal to 8, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₈:

the set is

${\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3\;}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\{j\; X_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\},{wherein}}\mspace{14mu}$${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}}$ ${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\;\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\;\frac{2\pi}{8}} & {\mathbb{e}}^{j\;\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\;\frac{3\pi}{8}} & {\mathbb{e}}^{j\;\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\;\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\;\frac{- \pi}{8}} \\{\mathbb{e}}^{j\;\frac{6\pi}{8}} & {\mathbb{e}}^{j\;\frac{14\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\;\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{\;{21\pi}}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\;\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2\;}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2\;}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2\;}}},{m \neq n},{m \in \left\{ {1,2,3,4} \right\}},{n \in {\left\{ {1,2,3,4} \right\}.}}$

Preferably, codebook space

₈, composed of two code words, is constructed through one of thefollowing construction methods.

Construction method 1:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 1 X 1 j ⁢ ⁢ X 1 - j ⁢ ⁢ X 1 ] } ; or 8 = {[ X 2 X 2 X 2 - X 2 ] , [ X 2 X 2 j ⁢ ⁢ X 2 - j ⁢ ⁢ X 2 ] } .

Construction method 2:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] } ;It shall be noted that Construction method 1 and Construction method 2can be realized by selecting any two from the set

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix}} \right\}.$

Codebook space

₈, composed of 4 code words, can be determined through one of thefollowing construction methods.

Construction method 3:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 1 X 1 j ⁢ ⁢ X1 - j ⁢ ⁢ X 1 ] , [ X 2 X 2 j ⁢ ⁢ X 2 - j ⁢ ⁢ X 2 ] } ;

Construction method 4:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] } .

It shall be noted that Construction method 3 and Construction method 4can be realized by selecting any 4 from the set

$\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\left\lbrack \begin{matrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{matrix} \right\rbrack,\left\lbrack \begin{matrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{matrix} \right\rbrack,\left\lbrack \begin{matrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{matrix} \right\rbrack,\left\lbrack \begin{matrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{matrix} \right\rbrack,\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix}} \right\}.$

Codebook space

₈, composed of 8 code words, can be determined through one of thefollowing construction methods.

Construction method 5:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] , ⁢ [ X m X n X m - X n ] , [ X m X n X m - Xn ] , [ X m X n X m - X n ] , [ X m X n X m - X n ] } ;(m ≠ n, m ∈ {1, 2, 3, 4}, n ∈ {1, 2, 3, 4})

Construction method 6:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] , ⁢ [ X 1 X 2 X 1 - X 2 ] , [ X 2 X 3 X 2 - X3 ] , [ X 3 X 4 X 3 - X 4 ] , [ X 4 X 1 X 4 - X 1 ] } ;

Construction method 7:

8 = { [ X 1 X 1 X 1 - X 1 ] , [ X 2 X 2 X 2 - X 2 ] , [ X 3 X 3 X 3 - X3 ] , [ X 4 X 4 X 4 - X 4 ] , ⁢ [ X 1 X 2 X 1 - X 2 ] , [ X 1 X 3 X 1 - X3 ] , [ X 1 X 4 X 1 - X 4 ] , [ X 2 X 3 X 2 - X 3 ] } .

It shall be noted that Construction Methods 5-7 can be realized byselecting any 4 from the set

$\quad\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix}} \right\}$and any 4 from the set

$\left\{ {{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\{j\; X_{m}} & {{{- j}\; X_{n}}\;}\end{bmatrix}}}} \right\}.$

Wherein

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank8 (RI=8) is provided,thus improving the precoding performance of the system in the case ofRank8 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, the codebook space

₈ is in the form of the multiplying of a fixed matrix M and anothercodebook space C8, and the product of M and C8 is equivalent to thecodebook space

₈, namely the codebook space

₈ can be in the form of the multiplying of a fixed matrix M and anothercodebook C8. Although the codebook space actually used is C8, it isrequired to multiply C8 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₈.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₈ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₈ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₈ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₈.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₈ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₈.

Preferably, when RI is equal to 7, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₇:

the set is

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{j\; Z_{3}} & {{- j}\; X_{3}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{{- j}\; Z_{3}} & {j\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{j\; Z_{4}} & {{- j}\; X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{{- j}\; Z_{4}} & {j\; X_{4}}\end{bmatrix},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{{- j}\; Z_{m}} & {j\; X_{n}}\end{bmatrix}}},{\bigcup\limits_{{m = 1},\;{m \neq n}}^{4}{\bigcup\limits_{n = 1}^{4}\begin{bmatrix}Z_{m} & X_{n} \\{j\; Z_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\}.}}}}}}}}}}}} \right.$

Codebook space

₇, composed of two code words, can be constructed through one of thefollowing construction methods.

Construction method 8:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] } ;

Construction method 9:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X 2 ] } ;

Construction method 10:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 1 X 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ X 1 ] } ;

Construction method 11:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] } ;

Construction method 12:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] } ;

Construction method 13:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ X 1 ] } ;wherein, in Construction methods 8 to 13, Z₁ and Z₂ are 4×3 matrixes, Z₁is composed of any 3 columns in X₁, and Z₂ is composed of any 3 columnsin X₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = {\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

It shall be noted that, the Construction methods 8-13 are realized byselecting any 2 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix}} \right\}.}}}} \right.$

Codebook space

₇, composed of 4 code words, can be constructed through one of thefollowing construction methods.

Construction method 14:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] , [ Z 2 X2 - Z 2 X 2 ] , [ Z 2 X 2 - j ⁢ ⁢ Z 2 j ⁢ ⁢ X 2 ] } ;

Construction method 15:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ X 1 ] , [ Z 2 X 2Z 2 - X 2 ] , [ Z 2 X 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ X 2 ] } ;

wherein, in Construction methods 14 and 15, Z₁ is composed of any 3columns in X₁, and Z₂ is composed of any 3 columns in X₂; or Z₁ iscomposed of any 3 columns in X₂, and Z₂ is composed of any 3 columns inX₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 16:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X2 ] , [ Z 2 X 2 Z 2 - X 2 ] } ;

wherein, in Construction method 16, Z₁ is composed of any 3 columns inX₁, and Z₂ is composed of any 3 columns in X₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = {\begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}.}}$

It shall be noted that Construction methods 14, 15 and 16 are realizedby selecting any 4 matrixes from the set

$\left\{ {{{{{\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix}\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix}}\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix}}{\left. \quad{{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix}\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix}}\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix}} \right\}.}} \right.$

Construction method 17:

7 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ;

Construction method 18:

7 = { [ Z 1 X 1 - Z 1 X 1 ] , [ Z 2 X 2 - Z 2 X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ,wherein, in Construction methods 17 and 18, Z₁ is composed of any 3columns in X₁, Z₂ is composed of any 3 columns in X₂, Z₃ is composed ofany 3 columns in X₃, and Z₄ is composed of any 3 columns in X₄; or Z₁ iscomposed of any 3 columns in X₁, Z₂ is composed of any 3 columns in X₃,Z₃ is composed of any 3 columns in X₂, and Z₄ is composed of any 3columns in X₄;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

It shall be noted that Construction methods 17 and 18 are realized byselecting any 4 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\{\; Z_{3}} & {- X_{3}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix}} \right\}.}}}} \right.$

By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank7 (RI=7) is provided,thus improving the precoding performance of the system in the case ofRank7 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, codebook space

₇ is in the form of the multiplying of a fixed matrix M and anothercodebook C7, and the product of M and C7 is equivalent to the codebookspace

₇, namely the codebook space

₇ can be in the form of the multiplying of a fixed matrix M and anothercodebook C7. Although the codebook space actually used is C7, it isrequired to multiply C7 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₇.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₇ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₇ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₇ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₇.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₇ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₇.

Preferably, when RI is equal to 6, any 2, 4, 8 or 16 matrixes areselected from the following to construct codebook space

₆.

the set is

$\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & Z_{3} \\Z_{3} & {- Z_{3}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\begin{bmatrix}Z_{3} & Z_{3} \\{j\; Z_{3}} & {{- j}\; Z_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\{j\; Z_{4}} & {{- j}\; Z_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},m}}{\overset{4}{\bigcup\limits_{n \neq 1}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {- Z_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},m}}{\overset{4}{\bigcup\limits_{n \neq 1}}\begin{bmatrix}Z_{m} & Z_{n} \\{j\; Z_{m}} & {{- j}\; Z_{n}}\end{bmatrix}}}} \right\}.}}}} \right.$

Codebook space

₆, composed of two code words, can be constructed by selecting any 2matrixes from the set below,

the set is

$\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix}} \right\}.$

Codebook space

₆ is determined through one of the following construction methods.

Construction method 19:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] } ;

Construction method 20:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] } ;

wherein, in Construction methods 19 and 20, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in X₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Codebook space

₆, composed of 4 code words, can be determined through one of thefollowing construction methods:

Construction method 21:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z 2Z 2 - Z 2 ] , [ Z 2 Z 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] } ;

Construction method 22:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] , [ Z 4 Z 4 Z 4 - Z 4 ] } ;

wherein, in Construction methods 21 and 22, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in Z₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$=Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄,

${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$

By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank6 (RI=6) is provided,thus improving the precoding performance of the system in the case ofRank6 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Codebook space

₆, composed of 8 code words, can be determined through one of thefollowing construction methods:

Construction method 23:

6 = [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z 3] , [ Z 4 Z 4 Z 4 - Z 4 ] , ⁢   [ Z 1 Z 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z 2j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] , [ Z 3 Z 3 j ⁢ ⁢ Z 3 - j ⁢ ⁢ Z 3 ] ,   [ Z 4 Z 4 j ⁢ ⁢ Z4 - j ⁢ ⁢ Z 4 ] } .

Construction method 24:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] , [ Z 4 Z 4 Z 4 - Z 4 ] ,   [ Z 1 Z 2 Z 1 - Z 2 ] , [ Z 1 Z 4 Z 1 -Z 4 ] , [ Z 2 Z 3 Z 2 - Z 3 ] , [ Z 2 Z 4 Z 2 - Z 4 ] } .

Codebook space

₆, composed of 16 code words, can be determined through one of thefollowing construction methods:

Construction method 25:

6 = { [ Z 1 Z 1 Z 1 - Z 1 ] , [ Z 2 Z 2 Z 2 - Z 2 ] , [ Z 3 Z 3 Z 3 - Z3 ] ,   [ Z 4 Z 4 Z 4 - Z 4 ] ,   [ Z 1 Z 2 Z 1 - Z 2 ] , [ Z 1 Z 4 Z1 - Z 4 ] , [ Z 2 Z 3 Z 2 - Z 3 ] , [ Z 2 Z 4 Z 2 - Z 4 ] ,   [ Z 1 Z 1j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 1 ] , [ Z 2 Z 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 2 ] , [ Z 3 Z 3 j ⁢ ⁢ Z3 - j ⁢ ⁢ Z 3 ] , [ Z 4 Z 4 j ⁢ ⁢ Z 4 - j ⁢ ⁢ Z 4 ] ,   [ Z 1 Z 2 j ⁢ ⁢ Z 1 - j ⁢⁢Z 2 ] , [ Z 1 Z 4 j ⁢ ⁢ Z 1 - j ⁢ ⁢ Z 4 ] , [ Z 2 Z 3 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 3 ] ,[ Z 2 Z 4 j ⁢ ⁢ Z 2 - j ⁢ ⁢ Z 4 ] } .

Preferably, codebook space

₆ is in the form of the multiplying of a fixed matrix M and anothercodebook C6, and the product of M and C6 is equivalent to the codebookspace

₆, namely the codebook space

₆ can be in the form of the multiplying of a fixed matrix M and anothercodebook C6. Although the codebook space actually used is C6, it isrequired to multiply C6 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₆.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₆ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₆ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₆ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₆.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₆ and any constant coefficient which is not 0 is an equivalenttransformation of the codebook space

₆.

Preferably, when RI is equal to 5, any 2, 4, 8 or 16 matrixes areselected from the following set to construct a codebook space

₅;

the set is

$\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\begin{bmatrix}Z_{1} & M_{1} \\{j\; Z_{1}} & {{- j}\; M_{1}}\end{bmatrix}{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {j\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{j\; Z_{2}} & {{- j}\; M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\begin{bmatrix}Z_{3} & M_{3} \\Z_{3} & {- M_{3}}\end{bmatrix}\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix}},\begin{bmatrix}Z_{4} & M_{4} \\Z_{4} & {- M_{4}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{j\; Z_{3}} & {{- j}\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{{- j}\; Z_{3}} & {j\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{j\; Z_{4}} & {{- j}\; M_{4}}\end{bmatrix},{\left. \quad{\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},\;{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 11}}\begin{bmatrix}Z_{m} & M_{j} \\{{- j}\; Z_{m}} & {j\; M_{j}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{j\; Z_{m}} & {{- j}\; M_{n}}\end{bmatrix}}}} \right\}.}}}}}}}}}}} \right.$

Codebook space

₅, composed of two code words, is determined through one of thefollowing construction methods:

Preferably, the construction methods below can be realized by selectingany 2 or 4 matrixes from the set

$\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {{- j}\; M_{1}}\end{bmatrix}{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{j\; Z_{1}} & {j\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{j\; Z_{2}} & {{- j}\; M_{2}}\end{bmatrix},{\left. \quad\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix} \right\}.}}}}}}}} \right.$

Construction method 26:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 2 M 2 Z 2 - M 2 ] } ;

Construction method 27:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M 2 ] } ;

Construction method 28:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 1 M 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ M 1 ] } ;

Construction method 29:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] } ,wherein, Z₁ is 4×3 matrix and is composed of any 3 columns in X₁; M₁ is4×2 matrix and is composed of any 3 columns in Z₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}};$

Construction method 30:

5 = { [ Z 1 M 1 Z 1 - M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] } ,wherein, Z₁ is 4×3 matrix and is composed of any 3 columns in X₁; M₁ is4×2 matrix and is composed of any 3 columns in Z₁;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}};$

Construction method 31:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 j ⁢ ⁢ Z 1 - j ⁢ ⁢ M 1 ] } ;

wherein, in Construction methods 23 to 28, Z₁ and Z₂ are 4×3 matrixes,Z₁ is composed of any 3 columns in X₁, and Z₂ is composed of any 3columns in X₂, M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3columns in Z₁, and M₂ is composed of any 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4}{\frac{1 - {\mathbb{i}}}{\sqrt{2}}.}}$

Codebook space

₅, composed of 4 code words, is determined through one of the followingconstruction methods:

Construction method 32:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] , [ Z 2 M2 - Z 2 M 2 ] , [ Z 2 M 2 - j ⁢ ⁢ Z 2 j ⁢ ⁢ M 2 ] } ;

wherein, Z₁ is composed of any 3 columns in X₁, and Z₂ is composed ofany 3 columns in Z₂; or Z₁ is composed of any 3 columns in X₂, and Z₂ iscomposed of any 3 columns in X₁;

M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3 columns in Z₁, andM₂ is composed of any 3 columns in Z₂,

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 33:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - j ⁢ ⁢ Z 1 j ⁢ ⁢ M 1 ] , [ Z 2 M 2Z 2 - M 2 ] , [ Z 2 M 2 j ⁢ ⁢ Z 2 - j ⁢ ⁢ M 2 ] } ;

wherein, in Construction methods 32 and 33, Z₁ is composed of any 3columns in X₁, and Z₂ is composed of any 3 columns in X₂; or Z₁ iscomposed of any 3 columns in X₂ and Z₂ is composed of any 3 columns inX₁; M₁, and M₂ are 4×2 matrixes, M₁ is composed of any 3 columns in Z₁,and M₂ is composed of any 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 34:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M2 ] , [ Z 2 M 2 Z 2 - M 2 ] } ;

wherein, in Construction methods 34, Z₁ is composed of any 3 columns inX₁, and Z₂ is composed of any 3 columns in X₂, M₁ and M₂ are 4×2matrixes, M₁ is composed of any 3 columns in Z₁, and M₂ is composed ofany 3 columns in Z₂;

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$

Construction method 35:

5 = { [ Z 1 X 1 Z 1 - X 1 ] , [ Z 2 X 2 Z 2 - X 2 ] , [ Z 3 X 3 Z 3 - X3 ] , [ Z 4 X 4 Z 4 - X 4 ] } ;

Construction method 36:

5 = { [ Z 1 M 1 - Z 1 M 1 ] , [ Z 2 M 2 - Z 2 M 2 ] , [ Z 3 M 3 Z 3 - M3 ] , [ Z 4 M 4 Z 4 - M 4 ] } ;

wherein, in Construction methods 35 and 36, Z₁ is composed of any 3columns in X₁, Z₂ is composed of any 3 columns in X₂, Z₃ is composed ofany 3 columns in X₃, and Z₄ is composed of any 3 columns in X⁴; or Z₁ iscomposed of any 3 columns in X₁, Z₂ is composed of any 3 columns in X₃,Z₃ is composed of any 3 columns in X₂, and Z₂₄ is composed of any 3columns in X₄; M₁ and M₂ are 4×2 matrixes, M₁ is composed of any 3columns in Z₁, and M₂ is composed of any 3 columns in Z₂; M₃ and M₄ are4×2 matrixes, M₃ is composed of any 3 columns in Z₃, and M₄ is composedof any 3 columns in Z₄.

${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{2\;\pi}{8}} & {\mathbb{e}}^{j\frac{10\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{15\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\;\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{7\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\;\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\;\pi}{8}} & {\mathbb{e}}^{j\frac{14\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{9\;\pi}{8}} & {\mathbb{e}}^{j\frac{21\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}}\end{bmatrix}.}}$By way of the preferable embodiment, the codebook space-based channelinformation feedback method in the case of Rank5 (RI=5) is provided,thus improving the precoding performance of the system in the case ofRank5 and achieving the effects of improving the throughput and systemfrequency spectrum efficiency.

Preferably, codebook space

₅ is in the form of the multiplying of a fixed matrix M and anothercodebook C5, and the product of M and C5 is equivalent to the codebookspace

₅, namely the codebook space

₅ can be in the form of the multiplying of a fixed matrix M and anothercodebook C5. Although the codebook space actually used is C5, it isrequired to multiply C5 and the matrix M to obtain the final code words,which is equivalent to the use of codebook space

₅.

Preferably, the exchange of any columns or any rows of the codebookspace is the equivalent transformation of the codebook space, namely,the codebook space

₅ can be the equivalent transformation of any column exchange, and thecolumn exchange, which will not change the characteristics of thecodebook space, is an equivalent transformation. Codebook space

₅ can also be the equivalent transformation of row exchange.

Preferably, the multiplying of any one column of the codebook space andany constant coefficient with a module of 1 is the equivalenttransformation of the codebook space, namely, the multiplying of any onecolumn of

₅ and any constant coefficient with a module of 1 is an equivalenttransformation of the codebook space

₅.

Preferably, the product obtained by multiplying all the columns of thecodebook space and any non-zero constant coefficient is equivalent tothe codebook space. Namely, the multiplying of all the columns of

₅ and any non-zero constant coefficient is an equivalent transformationof the codebook space

₅.

An LTE-A system is provided according to an embodiment of the presentinvention. FIG. 4 is the structural block diagram of the LTE-A system.As shown in FIG. 4, the system comprises a mobile terminal 2 as shown inFIG. 2 and a base station 4 as shown in FIG. 3. The detailed structuresof the mobile terminal 2 and the base station 4 are as shown in FIG. 2and FIG. 3, and details will not be given herein.

By way of the embodiments above, a terminal acquires the channelinformation; an RI and a PMI corresponding to the channel information isdetermined in a codebook space according to the channel information; andthe RI and PMI are sent to a base station, the problem that the codebookwith 4 antennae in the LTE system can not realize the channelinformation feedback in the LTE-A using 8 antennae, and the effects ofimproving the throughput of an LTE-A system and the frequency spectrumefficiency thereof is achieved.

Obviously, those skilled in the art shall understand that theabove-mentioned modules and steps of the present invention can berealized by using general purpose calculating device, can be integratedin one calculating device or distributed on a network which consists ofa plurality of calculating devices. Alternatively, the modules and thesteps of the present invention can be realized by using the executableprogram code of the calculating device. Consequently, they can be storedin the storing device and executed by the calculating device, or theyare made into integrated circuit module respectively, or a plurality ofmodules or steps thereof are made into one integrated circuit module. Inthis way, the present invention is not restricted to any particularhardware and software combination.

The descriptions above are only the preferable embodiment of the presentinvention, which are not used to restrict the present invention. Forthose skilled in the art, the present invention may have various changesand variations. Any amendments, equivalent substitutions, improvements,etc. within the principle of the present invention are all included inthe scope of the protection of the present invention.

What is claimed is:
 1. A method for sending channel information,comprising: a mobile terminal acquiring channel information; accordingto the channel information, determining, in a codebook space, a RankIndicator (RI) and a Precoding Matrix Indicator (PMI) corresponding tothe channel information; and sending the RI and the PMI to a basestation; wherein: when the RI is equal to 8, a codebook space

₈ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{j\; X_{1}} & {{- j}\; X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{j\; X_{2}} & {{- j}\; X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},\left. \quad{\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}X_{3} & X_{3} \\{j\; X_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{j\; X_{4}} & {{- j}\; X_{4}}\end{bmatrix},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}X_{m} & X_{n} \\{j\; X_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\},{{{wherein}X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{2\;\pi}{8}} & {\mathbb{e}}^{j\frac{10\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{15\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\;\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{7\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\;\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\;\pi}{8}} & {\mathbb{e}}^{j\frac{14\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{9\;\pi}{8}} & {\mathbb{e}}^{j\frac{21\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}}}} \right.$and/or, when the RI is equal to 7, a codebook space

₇ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{j\; Z_{1}} & {{- j}\; X_{1}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{{- j}\; Z_{1}} & {j\; X_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{j\; Z_{2}} & {{- j}\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{{- j}\; Z_{2}} & {j\; X_{2}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{j\; Z_{3}} & {{- j}\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{{- j}\; Z_{3}} & {j\; X_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{j\; Z_{4}} & {{- j}\; X_{4}}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{4} & X_{4} \\{{- j}\; Z_{4}} & {j\; X_{4}}\end{bmatrix},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & X_{n} \\{{- j}\; Z_{m}} & {j\; X_{n}}\end{bmatrix}}},{\underset{{m = 1},{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & X_{n} \\{j\; Z_{m}} & {{- j}\; X_{n}}\end{bmatrix}}}} \right\},}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, and Z₂ is composedof any 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$and/or, when the RI is equal to 6, a codebook space

₆ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},\begin{bmatrix}Z_{1} & Z_{1} \\{j\; Z_{1}} & {{- j}\; Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{j\; Z_{2}} & {{- j}\; Z_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & Z_{3} \\Z_{3} & {- Z_{3}}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\begin{bmatrix}Z_{3} & Z_{3} \\{j\; Z_{3}} & {{- j}\; Z_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\{j\; Z_{4}} & {{- j}\; Z_{4}}\end{bmatrix},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {- Z_{n}}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & Z_{n} \\{j\; Z_{m}} & {{- j}\; Z_{n}}\end{bmatrix}}}} \right\},}}} \right.$ wherein Z₁ and Z₂ are both 4×3matrixes, Z₁ is composed of any 3 columns in X₁, and Z₂ is composed ofany 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$═Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄, ${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{2\;\pi}{8}} & {\mathbb{e}}^{j\frac{10\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{15\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\;\pi}{8}}\end{bmatrix}},{{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{7\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\;\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\;\pi}{8}} & {\mathbb{e}}^{j\frac{14\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{9\;\pi}{8}} & {\mathbb{e}}^{j\frac{21\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}}\end{bmatrix}};}$ and/or, when the RI is equal to 5, a codebook space

₅ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows, the set is $\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{j\; Z_{1}} & {{- j}\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{{- j}\; Z_{1}} & {j\; M_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{j\; Z_{2}} & {{- j}\; M_{2}}\end{bmatrix},{\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix}\left. \quad{\begin{bmatrix}Z_{3} & M_{3} \\Z_{3} & {- M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\Z_{4} & {- M_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{j\; Z_{3}} & {{- j}\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{{- j}\; Z_{3}} & {j\; M_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{j\; Z_{4}} & {{- j}\; M_{4}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{{- j}\; Z_{2}} & {j\; M_{2}}\end{bmatrix},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & M_{j} \\{{- j}\; Z_{m}} & {j\; M_{j}}\end{bmatrix}}},{\underset{{m = 1},\;{m \neq n}}{\bigcup\limits^{4}}{\underset{n = 1}{\bigcup\limits^{4}}\begin{bmatrix}Z_{m} & M_{n} \\{j\; Z_{m}} & {{- j}\; M_{n}}\end{bmatrix}}}} \right\}},} \right.$ wherein Z₁ and Z₂ are both 4×3matrixes, Z₁ is composed of any 3 columns in X₁, Z₂ is composed of any 3columns in X₂, Z₃ is composed of any 3 columns in X₃, and Z₄ is composedof any 3 columns in X₄; or Z₁ is composed of any 3 columns in X₁, Z₂ iscomposed of any 3 columns in X₃, Z₃ is composed of any 3 columns in X₂,and Z₄ is composed of any 3 columns in X₄; M₁ and M₂ are both 4×2matrixes, M₁ is composed of any 3 columns in Z₁, and M₂ is composed ofany 3 columns in Z₂; M₃ and M₄ are both 4×2 matrixes, M₃ is composed ofany 3 columns in Z₃, and M₄ is composed of any 3 columns in Z₄;${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{2\;\pi}{8}} & {\mathbb{e}}^{j\frac{10\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{15\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\;\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\;\pi}{8}} & {\mathbb{e}}^{j\frac{7\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\;\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\;\pi}{8}} & {\mathbb{e}}^{j\frac{14\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\;\pi}{8}} \\{\mathbb{e}}^{j\frac{9\;\pi}{8}} & {\mathbb{e}}^{j\frac{21\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\;\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\;\pi}{8}}\end{bmatrix}.}}$
 2. The method according to claim 1, wherein after thestep of sending the RI and the PMI to the base station, the methodfurther comprises: the base station acquiring the RI and the PMI; andperforming downlink precoding operation according to the RI and the PMI.3. The method according to claim 2, wherein the codebook space is storedin both the mobile terminal and the base station.
 4. The methodaccording to claim 1, wherein the codebook is in a form of multiplying afixed matrix M by another codebook C, and the product of M and C isequivalent to the codebook.
 5. The method according to claim 1, whereinexchange of any columns of the codebook is an equivalent transformationof the codebook, and exchange of any rows of the codebook is anequivalent transformation of the codebook.
 6. The method according toclaim 1, wherein multiplying of any one column of the codebook and anyconstant coefficient with a module of 1 is an equivalent transformationof the codebook.
 7. The method according to claim 1, wherein the productobtained by multiplying all the columns of the codebook by any non-zeroconstant coefficient is equivalent to the codebook.
 8. A mobileterminal, comprising a hardware processor configured to execute thefollowing modules: a first acquiring module, configured to acquirechannel information; a determination module, configured to determine, ina codebook space, a Rank Indicator (RI) and a Precoding Matrix Indicator(PMI) corresponding to the channel information according to the channelinformation, and a sending module, configured to send the RI and the PMIto a base station; wherein: when the RI is equal to 8, a codebook space

₈ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}X_{1} & X_{1} \\{jX}_{1} & {- {jX}_{1}}\end{bmatrix},\left\lbrack \begin{matrix}X_{2} & X_{2} \\{jX}_{2} & {- {jX}_{2}}\end{matrix} \right\rbrack,\left\lbrack \begin{matrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{matrix} \right\rbrack,\left. \quad{\left\lbrack \begin{matrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{matrix} \right\rbrack,\begin{bmatrix}X_{3} & X_{3} \\{jX}_{3} & {- {jX}_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{jX}_{4} & {- {jX}_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\{jX}_{m} & {- {jX}_{n}}\end{bmatrix}}}} \right\},{{{wherein}X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}} \right.$and/or, when the RI is equal to 7, a codebook space

₇ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{jZ}_{1} & {- {jX}_{1}}\end{bmatrix},{\quad{\left\lbrack \begin{matrix}Z_{1} & X_{1} \\{- {jZ}_{1}} & {jX}_{1}\end{matrix} \right\rbrack,\begin{bmatrix}Z_{2} & X_{2} \\{jZ}_{2} & {- {jX}_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- {jZ}_{2}} & {jX}_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{jZ}_{3} & {- {jX}_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- {jZ}_{3}} & {jX}_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{jZ}_{4} & {- {jX}_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- {jZ}_{4}} & {jX}_{4}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{- {jZ}_{m}} & {jX}_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{jZ}_{m} & {- {jX}_{n}}\end{bmatrix}}}} \right\},}}}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁ and Z₂ is composedof any 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$and/or, when the RI is equal to 6, a codebook space

₆ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & Z_{1} \\{jZ}_{1} & {- {jZ}_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{jZ}_{2} & {- {jZ}_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & Z_{3} \\Z_{3} & {- Z_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & Z_{3} \\{jZ}_{3} & {- {jZ}_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\{jZ}_{4} & {- {jZ}_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {- Z_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\{jZ}_{m} & {- {jZ}_{n}}\end{bmatrix}}}} \right\},}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, and Z₂ is composedof any 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$═Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄, ${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}};}$ and/or when the RI is equal to 5, a codebook space

₅ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows, the set is $\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{jZ}_{1} & {- {jM}_{1}}\end{bmatrix},{\quad{\left\lbrack \begin{matrix}Z_{1} & M_{1} \\{- {jZ}_{1}} & {jM}_{1}\end{matrix} \right\rbrack,\begin{bmatrix}Z_{2} & M_{2} \\{jZ}_{2} & {- {jM}_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- {jZ}_{2}} & {jM}_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & M_{3} \\Z_{3} & {- M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & M_{4} \\Z_{4} & {- M_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & M_{3} \\{jZ}_{3} & {- {jM}_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- {jZ}_{3}} & {jM}_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{jZ}_{4} & {- {jM}_{4}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- {jZ}_{2}} & {jM}_{2}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{j} \\{- {jZ}_{m}} & {jM}_{j}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{jZ}_{m} & {- {jM}_{n}}\end{bmatrix}}}} \right\},}}}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, Z₂ is composed ofany 3 columns in X₂, Z₃ is composed of any 3 columns in X₃, and Z₄ iscomposed of any 3 columns in X₄; or Z₁ is composed of any 3 columns inX₁, Z₂ is composed of any 3 columns in X₃, Z₃ is composed of any 3columns in X₂, and Z₄ is composed of any 3 columns in X₄; M₁ and M₂ areboth 4×2 matrixes, M₁ is composed of any 3 columns in Z₁, and M₂ iscomposed of any 3 columns in Z₂; M₃ and M₄ are both 4×2 matrixes, M₃ iscomposed of any 3 columns in Z₃, and M₄ is composed of any 3 columns inZ₄; ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$
 9. The mobile terminal according to claim 8, whereinthe codebook is in a form of multiplying a fixed matrix M by anothercodebook C, and the product of M and C is equivalent to the codebook.10. The mobile terminal according to claim 8, wherein exchange of anycolumns of the codebook is an equivalent transformation of the codebook,and exchange of any rows of the codebook is an equivalent transformationof the codebook.
 11. The mobile terminal according to claim 8, whereinmultiplying of any one column of the codebook and any constantcoefficient with a module of 1 is an equivalent transformation of thecodebook.
 12. The mobile terminal according to claim 8, wherein theproduct obtained by multiplying all the columns of the codebook by anynon-zero constant coefficient is equivalent to the codebook.
 13. A basestation, comprising a hardware processor configured to execute thefollowing modules: a second acquiring module, configured to acquire aRank Indicator (RI) and a Precoding Matrix Indicator (PMI) correspondingto a codebook space; and a precoding module, configured to performdownlink precoding operation according to the RI and the PMI; wherein:when the RI is equal to 8, a codebook space

₈ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}X_{1} & X_{1} \\X_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\X_{2} & {- X_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{1} & X_{1} \\{jX}_{1} & {- {jX}_{1}}\end{bmatrix},\begin{bmatrix}X_{2} & X_{2} \\{jX}_{2} & {- {jX}_{2}}\end{bmatrix},{\quad{\begin{bmatrix}X_{3} & X_{3} \\X_{3} & {- X_{3}}\end{bmatrix},{\quad{\begin{bmatrix}X_{4} & X_{4} \\X_{4} & {- X_{4}}\end{bmatrix},\left. \quad{\begin{bmatrix}X_{3} & X_{3} \\{jX}_{3} & {- {jX}_{3}}\end{bmatrix},\begin{bmatrix}X_{4} & X_{4} \\{jX}_{4} & {- {jX}_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\X_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}X_{m} & X_{n} \\{jX}_{m} & {- {jX}_{n}}\end{bmatrix}}}} \right\},{{{wherein}X_{1}} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}}}}}}}} \right.$and/or, when the RI is equal to 7, a codebook space

₇ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & X_{1} \\Z_{1} & {- X_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & X_{1} \\{- Z_{1}} & X_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\Z_{2} & {- X_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- Z_{2}} & X_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & X_{1} \\{jZ}_{1} & {- {jX}_{1}}\end{bmatrix},{\quad{\left\lbrack \begin{matrix}Z_{1} & X_{1} \\{- {jZ}_{1}} & {jX}_{1}\end{matrix} \right\rbrack,\begin{bmatrix}Z_{2} & X_{2} \\{jZ}_{2} & {- {jX}_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & X_{2} \\{- {jZ}_{2}} & {jX}_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & X_{3} \\Z_{3} & {- X_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- Z_{3}} & X_{3}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & X_{4} \\Z_{4} & {- X_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- Z_{4}} & X_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & X_{3} \\{jZ}_{3} & {- {jX}_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & X_{3} \\{- {jZ}_{3}} & {jX}_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{jZ}_{4} & {- {jX}_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & X_{4} \\{- {jZ}_{4}} & {jX}_{4}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{- Z_{m}} & X_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{- {jZ}_{m}} & {jX}_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\{jZ}_{m} & {- {jX}_{n}}\end{bmatrix}}}} \right\},}}}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, and Z₂ is composedof any 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$and/or, when the RI is equal to 6, a codebook space

₆ is constructed by selecting any 2, 4, 8, or 16 matrixes from a set asfollows: the set is $\left\{ {\begin{bmatrix}Z_{1} & Z_{1} \\Z_{1} & {- Z_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\Z_{2} & {- Z_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & Z_{1} \\{jZ}_{1} & {- {jZ}_{1}}\end{bmatrix},\begin{bmatrix}Z_{2} & Z_{2} \\{jZ}_{2} & {- {jZ}_{2}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & Z_{3} \\Z_{3} & {- Z_{3}}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & Z_{4} \\Z_{4} & {- Z_{4}}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & Z_{3} \\{jZ}_{3} & {- {jZ}_{3}}\end{bmatrix},\begin{bmatrix}Z_{4} & Z_{4} \\{jZ}_{4} & {- {jZ}_{4}}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\Z_{m} & {- Z_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & Z_{n} \\{jZ}_{m} & {- {jZ}_{n}}\end{bmatrix}}}} \right\},}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, and Z₂ is composedof any 3 columns in X₂, ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}};}$═Z₃ is composed of any 3 columns in X₃, and Z₄ is composed of any 3columns in X₄, ${X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{{X_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}};}$ and/or, when the RI is equal to 5, a codebook space

₅ is constructed by selecting any 2, 4, 8 or 16 matrixes from a set asfollows, the set is $\left\{ {\begin{bmatrix}Z_{1} & M_{1} \\Z_{1} & {- M_{1}}\end{bmatrix},\begin{bmatrix}Z_{1} & M_{1} \\{- Z_{1}} & M_{1}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\Z_{2} & {- M_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- Z_{2}} & M_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{1} & M_{1} \\{jZ}_{1} & {- {jM}_{1}}\end{bmatrix},{\quad{\left\lbrack \begin{matrix}Z_{1} & M_{1} \\{- {jZ}_{1}} & {jM}_{1}\end{matrix} \right\rbrack,\begin{bmatrix}Z_{2} & M_{2} \\{jZ}_{2} & {- {jM}_{2}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- {jZ}_{2}} & {jM}_{2}\end{bmatrix},{\quad{\begin{bmatrix}Z_{3} & M_{3} \\Z_{3} & {- M_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- Z_{3}} & M_{3}\end{bmatrix},{\quad{\begin{bmatrix}Z_{4} & M_{4} \\Z_{4} & {- M_{4}}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{- Z_{4}} & M_{4}\end{bmatrix},\left. \quad{\begin{bmatrix}Z_{3} & M_{3} \\{jZ}_{3} & {- {jM}_{3}}\end{bmatrix},\begin{bmatrix}Z_{3} & M_{3} \\{- {jZ}_{3}} & {jM}_{3}\end{bmatrix},\begin{bmatrix}Z_{4} & M_{4} \\{jZ}_{4} & {- {jM}_{4}}\end{bmatrix},\begin{bmatrix}Z_{2} & M_{2} \\{- {jZ}_{2}} & {jM}_{2}\end{bmatrix},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & X_{n} \\Z_{m} & {- X_{n}}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{- Z_{m}} & M_{n}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{j} \\{- {jZ}_{m}} & {jM}_{j}\end{bmatrix}}},{\overset{4}{\bigcup\limits_{{m = 1},{m \neq n}}}{\overset{4}{\bigcup\limits_{n = 1}}\begin{bmatrix}Z_{m} & M_{n} \\{jZ}_{m} & {- {jM}_{n}}\end{bmatrix}}}} \right\},}}}}}}}}} \right.$ wherein Z₁ and Z₂ are both4×3 matrixes, Z₁ is composed of any 3 columns in X₁, Z₂ is composed ofany 3 columns in X₂, Z₃ is composed of any 3 columns in X₃, and Z₄ iscomposed of any 3 columns in X₄; or Z₁ is composed of any 3 columns inX₁, Z₂ is composed of any 3 columns in X₃, Z₃ is composed of any 3columns in X₂, and Z₄ is composed of any 3 columns in X₄; M₁ and M₂ areboth 4×2 matrixes, M₁ is composed of any 3 columns in Z₁, and M₂ iscomposed of any 3 columns in Z₂; M₃ and M₄ are both 4×2 matrixes, M₃ iscomposed of any 3 columns in Z₃, and M₄ is composed of any 3 columns inZ₄; ${X_{1} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}},{X_{2} = \begin{bmatrix}1 & 1 & 1 & 1 \\q_{1} & q_{2} & q_{3} & q_{4} \\{\mathbb{i}} & {- {\mathbb{i}}} & {\mathbb{i}} & {- {\mathbb{i}}} \\q_{2} & q_{1} & q_{4} & q_{3}\end{bmatrix}},{q_{1} = \frac{1 + {\mathbb{i}}}{\sqrt{2}}},{q_{2} = \frac{{- 1} + {\mathbb{i}}}{\sqrt{2}}},{q_{3} = \frac{{- 1} - {\mathbb{i}}}{\sqrt{2}}},{q_{4} = \frac{1 - {\mathbb{i}}}{\sqrt{2}}},{X_{3} = \begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{\pi}{8}} & {\mathbb{e}}^{j\frac{5\pi}{8}} & {\mathbb{e}}^{j\frac{{- 7}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}} \\{\mathbb{e}}^{j\frac{2\pi}{8}} & {\mathbb{e}}^{j\frac{10\pi}{8}} & {\mathbb{e}}^{j\frac{{- 14}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 6}\pi}{8}} \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{15\pi}{8}} & {\mathbb{e}}^{j\frac{{- 21}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 9}\pi}{8}}\end{bmatrix}},{X_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\{\mathbb{e}}^{j\frac{3\pi}{8}} & {\mathbb{e}}^{j\frac{7\pi}{8}} & {\mathbb{e}}^{j\frac{{- 5}\pi}{8}} & {\mathbb{e}}^{j\frac{- \pi}{8}} \\{\mathbb{e}}^{j\frac{6\pi}{8}} & {\mathbb{e}}^{j\frac{14\pi}{8}} & {\mathbb{e}}^{j\frac{{- 10}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 2}\pi}{8}} \\{\mathbb{e}}^{j\frac{9\pi}{8}} & {\mathbb{e}}^{j\frac{21\pi}{8}} & {\mathbb{e}}^{j\frac{{- 15}\pi}{8}} & {\mathbb{e}}^{j\frac{{- 3}\pi}{8}}\end{bmatrix}.}}$
 14. The base station according to claim 13, whereinthe codebook is in a form of multiplying a fixed matrix M by anothercodebook C, and the product of M and C is equivalent to the codebook.15. The base station according to claim 13, wherein exchange of anycolumns of the codebook is an equivalent transformation of the codebook,and exchange of any rows of the codebook is an equivalent transformationof the codebook.
 16. The base station according to claim 13, whereinmultiplying of any one column of the codebook and any constantcoefficient with a module of 1 is an equivalent transformation of thecodebook.
 17. The base station according to claim 13, wherein theproduct obtained by multiplying all the columns of the codebook by anynon-zero constant coefficient is equivalent to the codebook.
 18. AnLTE-A system, comprising: the mobile terminal according to claim 8 andthe base station according to claim 13.